Salmonella Typhimurium (ST) JOL389 and χ3339 are strong virulent strains against mouse. ST χ8554 is derived by deletion of the asd gene from ST χ3339. Plasmid pMMP184 carrying a ghost cassette was transformed into ST χ8554, and ST χ8554 ghost cells were prepared and administrated via the oral route to BALB/c mice. Change in the amount of total IgG was not elicited to boosting of single ST χ8554 ghost cells, but the content was increased from 6 weeks after the 3rd administration. However, when the ST JOL389 ghost cells is administered together with ST χ8554 ghost cells, the content of total IgG was increased in 2 weeks post primary administration. It was found that the content of total IgG of the group mixed with ST JOL389 ghost cells showed an increased value of 8 times or more at 10 weeks when compared with the group of ST χ8554 ghost cells. The content of IgG1, IgG2a, and sIgA in both groups increased from 4 weeks postprimary administration. As a challenge test of virulent ST χ3339, χ8554 (pMMP184) and χ8554 (pMMP184)/JOL389 ghost cell groups showed protection of 50% or more when compared to the control group. These results suggest that the preparation of combined ghost cells from a strong virulent ST increases immunity more than a single strain.